1. Field of the Invention
The present invention relates to a substrate processing system and a substrate processing method for subjecting, e.g., semiconductor wafers, glass for LCD substrates, etc. to cleaning and other treatments.
2. Related Background Art
Substrate processing systems for subjecting various treatments to semiconductor wafers (hereinafter called “wafers”) in, e.g., semiconductor device fabrication processes include processing liquid circuits for reusing processing liquids to be fed to the wafers. The processing liquid circuits include filters for removing foreign objects, etc. mixed in the processing liquids which have been used in processing the wafers, so that the processing liquids are purified to be fed again to the wafers. Foreign objects which are mixed in the processing liquids are, e.g., decomposed resist films. This foreign object is found in the step of feeding an organic solvent or a releasing chemical liquid to a resist applied to wafers to dissolve and remove the resist. That is, polymers produced on the surface of the resist film or decomposed resist film is not completely dissolved in the chemical liquid but peel off the wafers in film or colloidal foreign objects to be discharged together with the processing liquids which have been used in the processing. A filter for removing such foreign object, e.g., a cylindrical filter member is disposed in a housing, in which processing liquids containing the foreign objects are passed through the filter member from the outer circumference of the filter member to the inside thereof to thereby trap the foreign object on the outer circumference.
However, in the conventional substrate cleaning processing system, it is a problem that relatively large foreign objects fill the filter, specifically peeled polymers and decomposed resists, which are colloidal foreign objects, easily fill the filter. The filter is required to be frequently replaced, which is a cause for cost increase. The operation of replacing the filter interrupts the wafer cleaning processing, which is a cause for decrease of the throughput of the wafer processing as a whole.